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Genetics: DNA and inheritance

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The Hardy-Weinberg equilibrium states that allele frequencies remain constant across generations unless certain influences are introduced, such as nonrandom matings or mutations.

Describe the Hardy-Weinberg principle.
Are there influences that deviate from the principle? If so, what are they? If no, why?
Deoxyribonucleic acid (DNA) profiling is a tool used in forensic investigation and paternity testing. This technique is often used by forensic scientists to identify individuals on the basis of their DNA profiles.

How is DNA profiling performed?
What are some of the novel uses of DNA profiling, other than those described in your textbook?
Sickle-cell disease is an example of balanced polymorphism as carriers of this disease are protected against malaria.

Describe an example of balanced polymorphism, other than sickle-cell disease, glucose-6-phosphate dehydrogenase (G6PD) deficiency, phenylketonuria (PKU), prior protein mutation, cystic fibrosis (CF), and Smith-Lemli-Opitz syndrome (SLOS).

Genetic ancestry testing is becoming popular as more and more people are trying to trace their ancestry. Two different types of tests are generally offered, mitochondrial DNA, which traces maternal lineages, and Y chromosome testing, which traces paternal lineages.

Does genetic ancestry testing provide a complete picture of a person's heritage? If so, how? If not, why not?

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The Hardy-Weinberg principle stated that evolution will not occur in a population if seven conditions are met: 1) mutation is not occurring; 2) natural selections is not occurring ; 3) the population is infinitely large ; 4) all members of the population breed; 5) all mating is totally random; 6) everyone produces the same number of offspring; 7) there in no migration in or out of the population. If there is evolution, these conditions are absence. In other words, if no mechanisms of evolution are acting on a population, evolution will not occur, and the gene pool frequencies will remain unchanged. The Hardy Weinbergy equilibrium equation ( P2 + 2pq + q2 = 1) is defined as the frequency of the dominant allele allele and q as the frequency of recessive allele for a trait controlled by a pair of alleles ( A and a). In other words, p equals all of the alleles in individuals who are homozygous dominant (AA) and half of the alleles in people who are heterozygous ( Aa) for this trait in a population. The Hardy Weinberg principle predict how gene frequencies will be inherited from generation to generation given a set of specific set of assumptions. The Hardy Weinberg principles states that in a large randomly breeding population, allelic frequencies will remain the same from generation to generation assuming that there is no mutation, gene migration, selection, or genetic drift.

Are there influences that deviate from the principle? If so, what are they? If no, why?

There are influences that deviate from the principle because in the real natural world, you know that there is always mutation that deviate from the Hardy Weinberg equilibrium. Mutation can occur spontaneously or induced by environmental factors, such as radiation, ultraviolet light, sunlight, or x-rays. These mutagens can cause mutations that will allow evolution to take place. There is evolution, there is no Hardy Weinberg. Genetic drift can also happen in real life and natural selection as well. For example, we tend to choose our mate and this nonrandom mating will deviate from Hardy Weinberg equilibrium.

Deoxyribonucleic acid (DNA) profiling is a tool used in forensic investigation and paternity testing. This technique is often used by forensic scientists to identify individuals on the basis of their DNA profiles.

How is DNA profiling performed?

DNA profiling is a technique ...

Solution Summary

The Hardy-Weinberg principle stated that evolution will not occur in a population if seven conditions are met: 1) mutation is not occurring; 2) natural selections is not occurring ; 3) the population is infinitely large ; 4) all members of the population breed; 5) all mating is totally random; 6) everyone produces the same number of offspring; 7) there in no migration in or out of the population. This solution discusses this further.

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From Genes to Proteins, Mutations & Inheritance of Traits or Genetic Disorders

Part 1: Genetics - From Genes to Proteins, Mutations
Overview: Genetic information in DNA is transcribed to RNA and then translated into the amino acid sequence of a Protein.
A) Step 1 - Transcription: During the process of transcription, the information in the DNA codons of a gene is transcribed into RNA.
Suppose that gene X has the DNA base sequence 3'-TACCCTTTAGTAGCCACT-5'.
Question: What would be the base sequence of RNA after transcription occurs? Turn this in.
(In this particular example, assume that the RNA product does not require processing to become mRNA. In other words, the transcribed RNA becomes the mRNA sequence.)
B) Step 2 - Translation: During protein synthesis at the ribosome, the base sequence of the mRNA codons is translated to the amino acid sequence of a protein.
Question: Using the mRNA that you transcribed above, use the genetic code table to determine the resulting amino acid sequence? Turn this in.
And, turn in the answer to these questions:
What is the significance of the first and last codons? What meaning do these codons have for protein synthesis?
C) Mutations: A mutation is defined as a change in the base sequence of DNA. This may occur as a "mistake" in DNA replication, for example.
Suppose that during DNA replication, two mutant DNA sequences are produced as shown below.
For the 2 mutated DNA sequences, you will investigate how these changes might affect the sequence of amino acids in a protein.
Question: For each of the two, you will need to first transcribe the mRNA, and then use the genetic code table to determine the amino acid sequence.
Turn these in, and state whether the protein sequence changes for each.
Question: Then, explain why a change in amino acid sequence might affect protein function. Turn in your answer.
Here is the original sequence, followed by two mutated sequences, 1 and 2:
Original sequence 3'- TACCCTTTAGTAGCCACT-5'
Mutated sequence 1) 3'-TACGCTTTAGTAGCCATT-5'
Mutated sequence 2) 3'-TAACCTTTACTAGGCACT-5'.

Part 2: Inheritance of Traits or Genetic Disorders
Bob and Sally recently married. Upon deciding to plan a family, both Sally and Bob find out that they are both heterozygous for cystic fibrosis, but neither of them has symptoms of the disorder.
Set up and complete a Punnett Square for cystic fibrosis for this couple; turn in the Punnett square.
When doing the Punnett Square, C = normal allele; and c = allele for cystic fibrosis.
Note: You can use the Table function in MS Word to create and fill in a Punnett Square.
Questions:
Based on the Punnett square, calculate chances (percentages) for having a healthy child (not a carrier), a child that is a carrier for the cystic fibrosis trait, and a child with cystic fibrosis? Turn in these percentages.

Part 3: Cell division, sexual reproduction and genetic variability
Eukaryotic cells can divide by mitosis or meiosis. In humans, mitosis produces new cells for growth and repair; meiosis produces sex cells (gametes) called sperm and eggs.
Although mutations are the ultimate source of genetic variability, both meiosis and sexual reproduction also can contribute to new genetic combinations in offspring.
Question: How do both meiosis and sexual reproduction (fertilization) produce offspring that differ genetically from the parents? Be sure to talk about steps in meiosis that increase variability as well as the process of fertilization.

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